6 Common Types of Concrete Cracks and What They Mean

6 Common Types of Concrete Cracks and What They Mean

We often get asked about the causes behind concrete cracks. Customers wonder why they can appear even in a newly poured foundation.
There are various causes of cracks in concrete structures. Cracks such as plastic shrinkage cracks, settlement cracks, various types of cracks in fresh and hardened concrete and their methods of control are discussed.
When you see a crack in your concrete slab or wall, your first assumption is typically that something has been done wrong but that’s not always the case. Actually, concrete cracks are very common, some are even inevitable.

Causes of Cracking in Concrete

We explain 6 of the most common types of concrete cracks below.

1 Plastic Shrinkage Cracking “before concrete hardening”

The primary cause of plastic shrinkage cracking is the rapid drying out of concrete, which can cause the shrinkage strain of concrete to exceed its tensile strain capacity. The rate of evaporation of water from concrete can also be increased greatly by even the lightest of wind, at least doubling the chances of seeing shrinkage cracks develop these can create a series of parallel shrinkage cracks in one direction. The action of power floating effectively re-compacts concrete and closes plastic shrinkage cracks as they form.

2 Early Thermal Contraction Cracks “after hardening”

One of the most common questions is about cracks that are developing in newly poured concrete. Thick slabs subject to excess temperature gradients, followed by rapid cooling, can exhibit early thermal contraction cracks after one day and up to several weeks.

3 Long Term Drying Shrinkage Cracks “after hardening”

Long term drying shrinkage cracks are particularly prevalent in thin slabs subject to high shrinkage and in slabs which have insufficient stress relief. Cracks of this type can occur up to several years after casting.

4 Plastic Settlement Cracking “before concrete hardening”

Slabs with deep sections, or changes of depth, are mainly affected by plastic settlement cracking. The traditionally reinforced ground bearing floors should be detailed with a bottom mesh.
Source: ACIFC 2019

5 Poor Construction Practices

A wide variety of poor construction practices can result in cracking in concrete structures. Foremost among these is the common practice of adding water to concrete to improve work ability. Added water has the effect of reducing strength, increasing settlement, and increasing drying shrinkage.

6 Mud Cracks

Testing sand quality for concrete construction is as much of importance as other materials for concrete.
Mud cracking (painting) Drywall mud often cracks because it has dried too quickly or because the application was too thick.
Aggregate most of which pass through 4.50 mm is sieve is known as fine aggregate.
Fine aggregate shall consists of natural sand, crushed stone sand, crushed gravel sand stone dust or arable dust, fly ash and broken brick (burnt mud).
source: theconstructor